Incoherent-scattering factors for atomic helium using a density-matrix approach

Both the one- and two-electron contributions to the differential cross section (DCS) for the Compton scattering of x rays from atomic helium have been computed at the Hartree-Fock level. An asymmetry in the DCS about $q=0\mathrm{}$ is observed. The DCS has been used to obtain the incoherent-scattering factors for atomic helium and the results have been compared with the Waller-Hartree (WH) theory. It is found that the two-electron contribution is appreciable in the region of the small momentum transfer. The effect of the choice of the Breit-Dirac factor on the incoherent-scattering factors has also been studied.